1. Technical Field
This invention relates to an electric parking brake having a monitoring function.
2. Background Art
FIG. 8 shows an electric disk brake disclosed in the below-identified Patent document 1.
This electric disk brake includes an electric motor 1 and a linear motion mechanism 2 that are connected together through a speed reduction mechanism 3, and is configured such that the rotary motion of the motor 1 is transmitted to the linear motion mechanism 2 through the speed reduction mechanism 3 and the linear motion mechanism converts the rotary motion transmitted to a linear motion, thus pressing a brake pad (friction member) 4 against a brake disk 5.
This disk brake includes a locking mechanism 6 having a locking pin (pushrod) which provides the disk brake with the function of a parking brake too.
The locking mechanism 6 is configured to lock the linear motion mechanism 2 in position by bringing the locking pin into engagement with a planetary carrier 9 of a planetary gear mechanism forming the linear motion mechanism 2.
The locking mechanism 6 includes a solenoid 7 of which a plunger 8 and a spring are mounted in a bobbin. To lock the linear motion mechanism in position, the plunger 8, which serves as the locking pin, is pushed the spring until engaged in a recess H formed in the planetary carrier 9. To unlock the plunger 8, the plunger 8 is pulled by the solenoid 7 against the force of the spring until the plunger 8 is removed from the recess H.
In another conventional arrangement, as shown in FIG. 9, a plunger 8 having a conical head is configured to be engaged in a conical hole formed in a threaded roller device of a speed reduction mechanism. In still another conventional arrangement, as shown in FIG. 10, a plunger 8 in the form of an engaging claw is configured to be brought into engagement with a protrusion formed on the planetary carrier 9 of the linear motion mechanism.